17-year-old Claire Davis has been in the hospital since Friday's shooting at Arapahoe High School. Doctors say she is now stable but suffered severe head trauma. Her community is responding with a massive show of support for her and her family. Ana Cabrera has the latest.

The past year brought historic changes, democratic milestones, devastating tragedies, and acts of heroism that will never be forgotten.

In 2012 Anderson traveled across the country and around the world seeking the truth. He met people who were struggling against seemingly insurmountable odds: Syrian refugees, gunshot victims in Colorado, New Yorkers who lost everything they had, widows facing a harsh new reality.

There were crimes that divided communities and launched important conversations about discrimination and ethics. In some cases, justice was served. Convicted of child sex abuse, Jerry Sandusky will spend the rest of his life in prison.

In the wake of the deadly Aurora, Colorado movie theater shooting, Anderson Cooper talks to Brett Sokolow, Executive Director of The National Behavioral Intervention Team Association, threat assessment expert Barry Spodak, and Peter Read, whose daughter Mary Karen Read was killed in the Virginia Tech shooting. They offer insight on how to prevent future attacks by recognizing warning signs.

Earlier this week, CNN affiliate KMGH reported that the suspected gunman’s psychiatrist, Dr. Lynne Fenton, alerted University of Colorado’s threat assessment team with concerns that he could potentially be a danger to others. Sources told KMGH that no one contacted police about Fenton’s notification, and that the university threat team did not act because the suspect had already taken steps to withdraw from school and they had “no control over him.”

Citing the 2008 shooting at Northern Illinois University in which a student returned to campus a year-and-a-half after leaving and killed five people, Spodak suggests that threat assessment teams “think through the broader implications” of not sharing concerns about a student. “Wouldn’t you like to have every bit of information you can gather, within the campus setting, to understand their state of mind at the time that they leave?” he said.

Less than two weeks have passed since 22-year old violist Petra Anderson was shot four times in theater 9, but she is on the road to recovery with the help of her doctors, family and the healing power of music.

CNN’s Dr. Sanjay Gupta explained how music may be helping Petra recover. "If you think about trying to sing a song, for example, there are several different parts of your brain that are immediately harnessed," Gupta said. The tunes are often played by her boyfriend, who is a professional clarinet player. "In someone who is just learning to walk, if you find a song with a particular cadence to it, you can learn how to reestablish your rhythm," said Gupta.

Petra's recovery has been considered a "miracle," because the bullet that went through her brain was just millimeters from striking in a way that could have been more damaging and possibly deadly. "The bullet, if it had gone through a particular blood vessel in there, and there are several that are large, that would have been a catastrophic injury. If it would have been lower within the brain, it could have injured the brain stem," explained Gupta.

Colorado shooting survivor Petra Anderson is beating the odds. She's already walking and telling jokes after being shot four times in theater 9 of the Aurora multiplex just 11 days ago. Three shotgun pellets hit her arm, and one went through her nose into her brain.

You might remember, in the days following the massacre, there was talk that Petra had an unusual brain malformation that allowed her to survive that shotgun wound to her head. Doctors called it a "miracle." They still do, but there's no more talk of a brain malformation. They say amazingly the bullet hit at just the right angle to avoid causing catastrophic damage. If it had struck just one millimeter to the left or right there would be no talk of a "miracle." Instead, they'd be mourning her death. Thankfully, Petra is a survivor.

Petra, a 22-year-old aspiring composer, hopes to pick up her violin again and even go to graduate school for music this fall. But her ultimate goal is another "miracle" - one for her mother, who's battling cancer. Petra wants her mom to survive alongside her.

It’s been a week since a gunman stormed through an emergency exit, into a crowded movie theater, dressed head-to-toe in tactical gear and armed with several weapons. He fired on a helpless crowd, while his apartment was booby-trapped to cause more harm miles away.

After the chaos quieted, we learned 12 innocent lives ended and 58 survivors were wounded. Countless witnesses and loved ones are now coping with the trauma of the senseless violence. A week later, and the grieving process is so new for the families of those who died. Their reality is still setting in — life without their mother or father, sibling, child, cousin, best friend.

Since the massacre, AC360° has focused on the dozen dreams and futures cut short. We’re honoring the victims and what they lived for, not just talking about how they passed away. Anderson has spoken with family and friends who shared beautiful stories, funny memories and inspiring lessons they learned from those killed in Aurora, Colorado.

Pierce O’Farrill, a survivor of the Aurora, Colorado massacre, has a message for the gunman: “I forgive you.” O’Farrill was sitting in the third row, one seat from the aisle near the exit door where the shooter entered.

“It was like I could feel a cloud of evil walking into the theater,” he tells CNN’s Randi Kaye. “When I saw him, literally everything almost seemed like it stopped.”

O’Farrill was hit three times, twice in his left foot and once in his upper arm, where the bullet shattered the bone. He dove to the ground and covered his head. He tasted blood in his mouth. When the shooting stopped for a moment he tried to make it to the exit, but he collapsed.

His head was inches from the gunman’s boot. “I could feel him walking around me,” he says. Pierce, who is deeply spiritual, started praying and made peace with dying. Then he started thinking about his brother and father and realized he didn’t want them to blame god for his death.

Gordon Cowden, a father of four, was with two of his daughters when he was shot and killed in theater 9.

“We have strength but at moments you’ll just breakdown and lose it,” Brooke, who was with her father when he died, tells Anderson Cooper.

A makeshift memorial of 12 white crosses sits close to the Colorado theater. On the cross that has Gordon’s name written across the top, there is this message: “Dad, it was a surreal disorienting night, what was certain was your calling to us, I love you both.”

“My dad taught me what it meant to be a man. He was a father first and last and always,” says Gordon’s son, Weston. “He lived so passionately and lived life like it was supposed to be lived.”

Brooke reminisces about one of the last days she spent with her father. “We went to a local park where there was a concert going on and we actually danced at that concert and I’ll remember that dance for a very long time,” she says to Anderson.

If you'd like to donate in his memory, gifts may be made to the Gordon Cowden Children's Memorial Fund at any Chase Bank location.